Asynchronous or accumulating conveyor systems are well known and conventionally employ a continuously moving conveyor chain, belt, or other member forming an endless path for conveying workpieces successively past work stations or from one work area to another. Conventionally, the workpieces are supported on pallets which underlie fixturing on which a workpiece may be carried so that the pallet and workpiece overlie the conveyor member and project above the latter.
It often is necessary to arrest movement of one or more of the workpiece supports to enable one or more operations to be performed on the workpieces carried by such supports or to effect proper spacing between successive workpieces. However, it is preferred to enable the conveyor member to continue to move, thereby enabling workpieces other than those whose movement has been arrested to continue to travel along the path. This objective usually is obtained by the provision of a non positive driving coupling between each workpiece support and the conveyor member, the coupling being operable to enable conjoint movement of each workpiece support and the conveyor unless and until such time as movement of the workpiece support along the conveyor path is arrested.
Asynchronous conveyor constructions of the kind currently in use include endless conveyor members which travel in a closed path in a substantially horizontal plane. Known asynchronous conveyors also include what is known as over-and-under conveyors wherein an endless conveyor member has vertically spaced upper and lower runs to which are non positively coupled workpiece supports that enable workpieces to be transferred longitudinally along the upper run, the lower run, or both. The non positive coupling means enables the workpiece supports to move conjointly with the conveyor member or be arrested while the conveyor member continues to move.
Although the known prior art asynchronous conveyors function satisfactorily in many instances, the height at which the workpieces are supported often are at a level which is not ergonomically appropriate. Further, the conventional asynchronous conveyors often do not provide as many work stations that may be desirable. In addition, some of such known conveyors lack convenient access for maintenance and repair purposes.
In addition to the foregoing, many of the conventional asynchronous conveyors do not lend themselves to the most efficient utilization of available floor space since the conveyor members associated with such conveyor systems impose limitations on the kinds of turns which the conveyor member may negotiate.
A principal objective of the invention is to provide an asynchronous conveyor construction which overcomes the disadvantages referred to above.